[mjc]

I've owned the '06 Z06 for about a year and this car gives me even more reason to hate winter. It's the first Corvette, and the most powerful car I've ever owned so I'm learning to drive it differently than my Gen4 Z28. I haven't turned off the traction control yet though it has bothered me once or twice. Oh yeah, the length of the driveway and the number of 2x10's required to get it off the ground is impressive. And there's the choreography needed to get it over the end of the driveway...I can now do it on the first try about half the time.

The one frightening thing is this head issue, or non-issue according to some. There is nothing definitive it seems, except for the fear of losing an engine and much of a short driving season. So I'm going to take the plunge, get the heads fixed and tweaked a bit, and this is what motivates me to write.

While the top of the engine is off, a few preventative maintenance issues have been suggested. And for a little more, I could have a "mild cam" and a tune that should register against my calibrated butt. It will be a long time before I can say that I know how to use all of the power already there...but...well, we are at 5000 feet; that's pretty thin justification and I may have to go with it. BUT, I live where there is a mandatory emission test. Here's the question:

What, if any, cam or cam characteristics will allow this (unmodified) car to pass Colorado Emissions tests? I'd really appreciate hearing actual recent experience -- much of what I've read here is quite old.

Thanks in advance,
mjc

 

[racingvette]

When intake manifold is off be a good time to replace both knock sensors, they are cheap in cost and easy to swap out
Use some silicon and make a dam around the top of recess which will prevent any water draining down to sensors and screwing them up.

If going with CAM, etc, either send your fuel injectors out and have them resized and matched flow
Or buy new ones but do not go too big as PCM will hate it

As to CAM consider what the LSA of the grind is, look at stock grind maybe 119 LSA now
The more narrow the LSA is the less vacuum there will be from startup to mid RPM range and make it tougher
on idle and passing smog tests.
If street driven a lot would not go lower then like a 114 LSA.
Many LS7s lost with crap CAM grinds that put rods out of that 427 CI block

At 5,000 feet elevation would be even worse with too narrow LSA because you have less density also means less vacuum.
Maybe losing 50 flywheel HP at that elevation and in hot weather less density and higher D.A loss.

Do not get sucked into some high priced "Dyno" tune, as really cannot see what is needed in tune changes for that loss of vacuum.
Need a good tuner who can do street tunes for the mods you do.